These tiny robots are powered by what?

Called hygrobots, these little worm-like robots can wriggle around and inch themselves forward without using batteries or electricity.

Developed by a team of researchers from Seoul National University in South Korea, the hygrobots absorb the natural humidity in the air around them in order to move. They were inspired by the way that plants use the water they absorb from the water or air to change in shape and size. The team envisions a variety of future applications for these robots, including drug delivery using the moisture on human skin.